The Oak Hill Youth Center, open since 1967 and plagued with the predictible issues of violence and failings one might suspect from a D.C. youth detention center, officially closes today. The last kids arrived yesterday at the New Beginnings Youth Center, not far from Oak Hill in Laurel, Md., where Mayor Adrian Fenty will be on hand today for its opening ceremony. The new campus is spacious and technologically advanced, with electronic key cards, floor-to-ceiling…